1. Technical Field
The subject matter described herein generally relates to vehicles that employ electric motors and, in particular, multiple-battery configurations used to supply power to such vehicles.
2. Description of the Related Art
It is generally agreed that reducing toxic emissions on a global scale will require alternatives to gasoline-powered and diesel-powered internal combustion engines currently used in vehicles, especially in automobiles and trucks. The need for emission reduction becomes greater as more people throughout the world acquire engine-powered vehicles, and as pollution levels in emerging commercial centers become increasingly unmanageable.
One viable solution is to encourage the use of electric personal transport vehicles, including automobiles, motorcycles, golf carts, scooters, and the like, where they are feasible. It is especially advantageous to promote the use of “clean energy” vehicles having zero tail pipe emission in the most densely populated metropolitan areas of Asia, for example, cities in China, Taiwan, Korea, and India. In the past, these areas have relied successfully on the use of bicycles for personal transport, but have in recent years replaced bicycles with combustion engine-powered vehicles. Substituting electric vehicles is a way to reduce tail pipe emissions to zero while also lowering overall pollution, because sources of electricity for recharging electric vehicles also tend to be clean energy sources. For example, electrical power may be generated from renewable sources (e.g., solar, hydro), or it may be generated at generation plants that produce no air pollution (e.g., nuclear plants). Also for example, electricity may be generated at plants that burn relatively clean burning fuels (e.g., natural gas), which have higher efficiency than internal combustion engines, and/or which employ pollution control or removal systems (e.g., industrial air scrubbers) which are too large, costly or expensive to install on board individual vehicles.
One barrier to adoption of electric motors for vehicles is that electric motors tend to be under-powered compared to their gasoline engine counterparts. Consequences of engine power constraints for electric vehicles in particular include limiting their range before charging is necessary, and hampering their usefulness in hilly areas or in off-road conditions. Thus, to achieve a high market penetration of electric vehicles worldwide in the more remote areas, and in areas with more challenging terrain, technological advances are needed to improve the efficiency of power delivery for electric vehicles.